Method for coating a ceramic matrix composite substrate with at least one coating, and corresponding part

Abstract

The invention relates in particular to a method for coating a ceramic matrix composite substrate (1) with at least one coating (4) forming an environmental barrier, comprising the following steps: E1: formation of a silicon-based bonding sublayer (2) over said ceramic matrix composite substrate (1); E2: formation of an environmental barrier coating (4) over said silicon-based bonding sublayer (2), characterized in that it comprises an additional step Eadd of forming at least one hexagonal phase TaN layer (5) above or below said silicon-based bonding sublayer (2). Figure 2.

Description

Title of the invention: Method for coating a ceramic matrix composite substrate with at least one coating, and corresponding part

[0001] GENERAL TECHNICAL DOMAIN

[0002] The present invention relates in particular to a method of coating a ceramic matrix composite material substrate with at least one coating forming an environmental barrier, particularly for aeronautics. STATE OF THE ART

[0003] Improving the efficiency of aircraft engines and complying with regulations on atmospheric emissions implies an increase in the operating temperatures of turbojet engines.

[0004] To achieve this, ceramic matrix composite materials (abbreviated CMC for "Ceramic Matrix Composite") based on silicon carbide SiC / SiC are in particular being developed for integration into new generation high-pressure turbines, in place of metallic superalloys.

[0005] Due to their lower density and better temperature resistance, these materials make it possible to reduce the mass of the engine and also to increase the combustion temperature.

[0006] However, these ceramic matrix composite materials (hereinafter referred to as CMC) are sensitive to oxidation / corrosion phenomena in the high temperature ranges concerned.

[0007] Indeed, in the presence of water vapor, SiC reacts with the oxidizing species to form silica according to equation 1 reproduced below, then the latter reacts with water vapor to form a volatile reaction product in the form of hydroxides Si(OH)4(g), according to equation 2 below:

[0008] [Chem. 1] SiC(M+3H2O(gW SiO2(s)+3H2+CO(g) (Equation 1);

[0009] [Chem. 2] SiO2(s) + 2H2O(g)—>Si(OH)4(g) (Equation 2),

[0010] equations in which (s) means solid and (g) means gas.

[0011] This oxidation / recession gradually consumes the ceramic matrix composite and limits its lifespan.

[0012] Environmental barrier coatings (abbreviated EBC for "Environmental Barrier Coating") made of rare earth disilicate have been developed and implemented to protect SiC / SiC ceramic matrix composite materials from the oxidizing / corrosive environment, which notably consists of CMAS (for Calcium, Magnesium, Aluminium and Silicon oxides: CaO-MgO-Al2O3-SiO2).

[0013] These barriers partially limit the diffusion of oxidizing species, but a layer of silica (SiO2) can form on the surface of the ceramic matrix composite.

[0014] The formation of this oxide layer is problematic because it is accompanied by the formation of gaseous species (CO(g)) which accumulate under the coating and form pores degrading the composite / coating adhesion.

[0015] To overcome this drawback, and in an oxidizing atmosphere under dry air, a silicon (Si)-based bonding layer, called an intermediate layer, is deposited on the surface of the ceramic matrix composite. It acts as a sacrificial layer because it oxidizes instead of the CMC, forming a protective silica layer called a "passivating" layer (also known as TGO for "Thermally Grown Oxide") according to equation 3:

[0016] [Chem. 3] SiC(s)+1.5 O2(g)—>SiO2(s)+CO(g) (Equation 3)

[0017] This silicon layer limits the operating temperature of the environmental barriers, due to the melting point of silicon which is 1414°C.

[0018] The attached [Fig. 1] shows the current architecture of an environmental barrier system. In this figure, the CMC substrate and the various layers covering it are represented purely symbolically and their respective thicknesses are not shown to scale.

[0019] In this figure: - Reference 1 designates a CMC substrate such as an aeronautical part. - Reference 2 designates a Si layer, referred to as a bonding layer, adhesion layer or sub-layer. It ensures the mechanical bond between the two layers located above and below it, as well as protection against oxidation of the substrate. - Reference 3 designates a silica layer, described as an oxide layer or TGO, which constitutes a final barrier against oxidation. - Reference 4 designates a rare earth disilicate layer, referred to as the top coat, which provides a barrier against oxidation and protection against volatilization. It constitutes the environmental barrier.

[0020] However, it is observed that the oxidation of silicon into silica (crystallized in the form of cristobalite) is accompanied by a volumetric expansion of the order of 120%.

[0021] Upon cooling, the phase transformation of cristobalite (from phase [3 to phase a), accompanied by a volumetric contraction of the order of 4 - 5 % leads to the development of stresses, which cause cracking of the oxide layer.

[0022] Continuous exposure to thermal cycling leads to the propagation of these cracks and to delamination of the coating.

[0023] This damage mechanism has been identified as the most critical. The weakening of the layer 3 / layer 4 interface, due to the growth of the cristobalite layer during exposure to the oxidizing / corrosive atmosphere, limits the lifespan of the environmental barriers.

[0024] The degree of embrittlement of this interface depends on the duration and temperature of aging.

[0025] Furthermore, rare earth disilicates are semi-transparent at the target operating temperatures and wavelengths below 5 pm, which leads to the absorption and propagation of the heat flux to the substrate, by radiative transfer.

[0026] This can lead to accelerated oxidation kinetics of the bonding layer.

[0027] The present invention aims to overcome these drawbacks. PRESENTATION OF THE INVENTION

[0028] To this end, the invention relates to a method of coating a ceramic matrix composite substrate with at least one coating forming an environmental barrier, which comprises the following steps:

[0029] El: formation of a silicon-based bonding sublayer above said ceramic matrix composite material substrate;

[0030] E2: formation of an environmental barrier coating over said silicon-based bonding sublayer,

[0031] characterized in that it comprises an additional step Eadd of forming at least one layer of TaN in hexagonal phase above or below said silicon-based bonding sublayer.

[0032] Thus, thanks to the introduction of said at least one layer of tantalum nitride in hexagonal phase, a high fraction of the radiative flux to which the substrate is subjected in CMC is reflected, which makes it possible to reduce the temperature of the substrate / environmental barrier interface.

[0033] In addition, there is an increased resistance of the assembly to oxidation and corrosion at the high temperatures of interest.

[0034] Finally, when tantalum nitride is present in the form of several distinct layers, crack propagation is reduced by the multiplication of interfaces.

[0035] According to other advantageous and non-limiting features of this process, taken alone or in any technically compatible combination, of at least two of them:

[0036] - said additional step Eadd is implemented so as to form said at less one layer of hexagonal-phase TaN beneath said silicon-based bonding sublayer, such that said at least one layer of hexagonal-phase TaN hexagonal is intercalated between said silicon-based bonding sublayer and said ceramic matrix composite material substrate;

[0037] - said additional step Eadd is implemented so as to form said at at least one layer of hexagonal phase TaN above said silicon-based bonding sublayer, so that said at least one layer of hexagonal phase TaN is intercalated between said silicon-based bonding sublayer and said environmental barrier coating;

[0038] - a form is formed between said silicon-based bonding sublayer and said at least a layer of TaN in hexagonal phase, at least one layer of metallic tantalum;

[0039] - said additional step Eadd is implemented by a spraying process cathode ray tube in high-power pulse regime;

[0040] - said additional step Eadd is implemented until a layer is obtained with a thickness between 1 nanometer and 50 micrometers, preferably between 20 nanometers and 5 micrometers;

[0041] - said at least one layer of TaN in hexagonal phase exhibits a reflectivity minimum hemisphericity of 50% in the range of wavelengths between 0.1 and 6 micrometers;

[0042] - said additional step Eadd comprises the formation of at least two layers distinct from TaN in hexagonal phase;

[0043] - said silicon-based bonding sublayer is formed of silicon, of silicon doped with boron, silicon doped with hafnium oxide, rare earths consisting of yttrium, ytterbium and gadolinium with additions of dopants consisting of zirconium, hafnium, tantalum, nitrogen, aluminium, SiAlON, Si-HfB2, SiC-HfO2, or SiC-HfO2-HfB2;

[0044] - said step El is implemented by implementing one of the following processes: physical evaporation deposition PVD, atmospheric pressure plasma spraying APS, high-speed flame powder deposition HVOF, low pressure plasma spraying LPPS, inert atmosphere plasma spraying IPS, chemical evaporation deposition CVD, vapor phase aluminization APVS, flash sintering, electrolytic deposition, slip, sol-gel;

[0045] - said environmental barrier coating is selected from disilicates rare earth Re2Si2O7, where Re = Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Yb, Dy, Ho, Er, Tm, Tb, Lu) and the corresponding co-doped disilicates, rare earth silicates Re2SiO5 and the corresponding co-doped silicates, barium strontium taluminosilicate (BaO)x.(SrO)i x.Al2O3.2SiO2 with 0 < x < 1), hafnium-doped rare earth silicates, rare earth-doped hafnium, mullite, spinels MgAl2O4, gamets (Y3Al5Oi2), partially / fully stabilized zirconias and possibly doped, the delta phases of A4B30i2 where A = yttrium, lanthanum or lutetium and where B = zirconium or hafnium, composites including Y2O3 in combination with ZrO2 and / or A12O3 and / or TiO2, hexa-aluminates, complex perovskites, as well as mixtures of at least two of these components;

[0046] - said step E2 is implemented by one of the following methods: plasma projection atmospheric pressure APS, vacuum plasma spraying, plasma spraying, including under very low pressure, suspension plasma spraying SPS, solution plasma spraying SPPS, high-speed flame powder HVOF, high-speed flame liquid HVSFS, electron beam evaporation EB-PVD, PVD vapor phase deposition, sol-gel, slurry, electrophoresis, or flash sintering;

[0047] - said substrate is part of a turbomachine component, such as a blade, a distributor and / or a high-pressure turbine ring sector.

[0048] The invention also relates to a part comprising a substrate made of ceramic matrix composite material, particularly for aeronautics, which comprises:

[0049] - a silicon-based bonding sublayer above said material substrate ceramic matrix composite;

[0050] - an environmental barrier coating over said underlayer silicon-based bonding;

[0051] characterized in that it also comprises at least one layer of TaN in hexagonal phase above or below said silicon-based bonding sublayer.

[0052] According to one possible embodiment, said at least one layer of hexagonal phase TaN is intercalated between said silicon-based bonding sublayer and said ceramic matrix composite material substrate.

[0053] According to another possible embodiment, said at least one layer of hexagonal phase TaN is intercalated between said silicon-based bonding sublayer and said environmental barrier coating.

[0054] According to yet another variant, it comprises, between said silicon-based bonding sublayer and said at least one layer of TaN in hexagonal phase, at least one layer of metallic tantalum. DESCRIPTION OF THE FIGURES

[0055] Other features and advantages of the invention will become apparent from the description which will now be given, with reference to the attached drawings, which represent, by way of indication but not limitation, possible embodiments.

[0056] On these drawings:

[0057] [Fig.1] illustrates schematically and as indicated above, a stack of layers comprising an environmental barrier, above a CMC substrate, in accordance with the prior art;

[0058] [Fig.2] schematically illustrates a stack of layers comprising an environmental barrier, above a CMC substrate, a stack obtained according to an embodiment of the present invention;

[0059] [Fig.3] schematically illustrates a stack of layers comprising an environmental barrier, above a CMC substrate, a stack obtained according to another embodiment of the present invention;

[0060] [Fig.4] is a graph which shows as a function of the wavelength of the incident light, the percentage of transmission of a hexagonal tantalum nitride film manufactured by an RF (radio frequency) technique and by a HIPIMS process;

[0061] [Fig.5] schematically illustrates a stack of layers comprising an environmental barrier, above a CMC substrate, a stack obtained according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0062] In the detailed description that follows, the formation of an environmental barrier on the surface of a silicon-containing CMC material substrate is considered. It should be noted, however, that the invention is applicable to a part made of silicon-containing ceramic matrix composite material and, more generally, to a part of which at least an adjacent portion is coated with a layer of silicon.

[0063] The silicon-containing CMC material substrate includes a fibrous reinforcement which can be made of carbon (C) fibers or ceramic fibers, for example SiC fibers.

[0064] The object of the invention generally consists of a method for coating a ceramic matrix composite material substrate with at least one coating forming an environmental barrier, which comprises the following steps, which are known per se:

[0065] - El: formation of a silicon-based bonding sublayer above said substrate made of ceramic matrix composite material;

[0066] - E2: formation of an environmental barrier coating over said silicon-based sublayer,

[0067] According to the invention, this process is characterized in that it includes an additional step Eadd of forming at least one layer of TaN in hexagonal phase above or below said silicon-based bonding sublayer.

[0068] A first embodiment comprises coating a ceramic matrix composite substrate (SiC / SiC) previously coated with a bonding underlayer, by a coating with high reflectivity which resists oxidation / corrosion under high temperature steam, due to its chemical composition and dense and homogeneous microstructure, then a layer or stack of layers called environmental barrier (i.e. resistant to oxidation, corrosion, CMAS type molten sands (CaO-MgO-Al2O3-SiO2), particulate erosion, etc).

[0069] Such stacking makes it possible to increase the overall life of ceramic matrix composite materials (SiC / SiC).

[0070] Another embodiment includes functionalizing a ceramic matrix composite substrate (SiC / SiC) with a highly reflective coating resistant to oxidation / corrosion under high-temperature steam due to its chemical composition and dense and homogeneous microstructure, then a bonding underlayer, and finally a layer or stack of layers called an environmental barrier (i.e., resistant to oxidation, corrosion, CMAS (CaO-MgO-Al2O3-SiO2) type molten sands, particulate erosion, etc.).

[0071] Such stacking makes it possible to increase the overall life of ceramic matrix composite materials (SiC / SiC).

[0072] According to the invention, this high reflectivity coating resistant to oxidation / corrosion at high temperature consists of tantalum nitride in its hexagonal phase.

[0073] Preferably, the Eadd step of the formation of this tantalum nitride is carried out by the high power pulse magnetron sputtering process (also known by the acronym HIPIMS for "High Power Impulse Magnetron Sputtering").

[0074] Such a process is described in document FR 3097237.

[0075] As a reminder, this process of coating a substrate with tantalum nitride by high-power pulsed magnetron sputtering technique, consists in the fact that a tantalum target is used and the coating of the substrate is carried out under an atmosphere containing nitrogen, the polarization of the target being controlled during the coating by imposing on it the superposition of a continuous polarization at a potential between -300 V and -100 V and a pulsed polarization whose pulses have a potential between -1200 V and -400 V.

[0076] It is of course possible to use another deposition method.

[0077] However, the advantage of the HIPIMS process lies in its ability to control the crystallinity of the deposited material (i.e. tantalum nitride in its hexagonal allotropic form) as a function of several parameters, including the nitrogen composition of the plasma, the temperature, the electrical parameters of the discharge, etc.

[0078] According to one possible embodiment, the TaN coating has a thickness of 1 nanometer to 50 micrometers, preferably from 50 nanometers to 5 micrometers.

[0079] Such a coating makes it possible to obtain a minimum hemispherical reflectivity of 50% in the range of wavelengths of interest, i.e. from 0.1 to 6 micrometers.

[0080] The attached [Fig.4] illustrates the percentage transmission T of a hexagonal phase TaN film with a thickness of 10 nanometers over a wavelength measurement range from 0 to 10,000 nanometers.

[0081] It is observed that the reflectivity (1 - Transmission) of this film is greater than 50% for the wavelengths considered.

[0082] This specific property therefore makes it possible to decrease the oxidation kinetics of the bonding sublayer by reducing the temperature at the bonding sublayer / TaN coating interface.

[0083] Once the environmental protection has worn away, this highly reflective and high-temperature anti-oxidation / corrosion TaN layer will take over to, at a minimum, increase the lifespan of the CMC substrate. This is due to the thermal stability of this coating, its compatibility in terms of coefficient of thermal expansion, which is close to that of the CMC substrate, as well as its resistance to oxidation and corrosion.

[0084] According to one possible embodiment, the TaN coating can be deposited in the form of at least two superimposed and distinct layers, so as to multiply the interfaces, which limits the propagation of cracks created by thermal cycles in operation.

[0085] According to one possible embodiment, the silicon-based bonding sublayer is formed of silicon, boron-doped silicon, hafnium oxide-doped silicon, rare earths consisting of yttrium, ytterbium and gadolinium with additions of dopants consisting of zirconium, hafnium, tantalum, nitrogen, aluminum, SiAlON, Si-HfB2, SiC-HfO2, or SiC-HfO2-HfB2.

[0086] According to one possible embodiment, the aforementioned step El can be carried out, but not exclusively, by one of the following processes: physical vapor deposition (PVD), atmospheric plasma spraying (APS), high velocity oxygen fuel (HVOF), low pressure plasma spraying (LPPS), inert plasma spraying (IPS), chemical vapor deposition (CVD), vapor aluminization (APVS), flash sintering, electrolytic deposition, slurry, sol-gel.

[0087] According to one possible embodiment, the environmental layer coating is selected from rare-earth disilicates Re2Si2O7 (where Re = Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Yb, Dy, Ho, Er, Tm, Tb, Lu) and the corresponding co-doped disilicates, rare-earth silicates Re2SiO5 and the corresponding co-doped silicates, barium strontium aluminosilicate (BaO)x.(SrO)i X.A12O3 .2SiO2 with 0 < x < 1), hafnium-doped rare-earth silicate, rare-earth-doped hafnium, mullite, spinels MgAl2O4, garnets (Y3Al5Oi2), partially / fully stabilized and optionally doped zirconias, and A4B3O delta phases 12 where A = yttrium, lanthanum or lutetium and where B = zirconium or hafnium, composites including Y2O3 in combination with ZrO2 and / or A12O3 and / or TiO2, hexa-aluminates, complex perovskites, and mixtures of at least two of these components.

[0088] According to one possible embodiment, the aforementioned step E2 is implemented by one of the following processes: atmospheric pressure plasma spraying APS, vacuum plasma spraying, plasma spraying, including under very low pressure, suspension plasma spraying SPS (for Suspension Plasma Spraying), solution plasma spraying SPPS (for Solution Precursor Plasma Spraying), high velocity flame powder spray HVOF, high velocity flame liquid spray HVSFS (for High Velocity Suspension Flame Spray), electron beam physical vapor deposition EB-PVD, PVD vapor phase deposition, sol-gel, slurry electrophoresis, or flash sintering.

[0089] Figures 2, 3 and 4 show three examples of layer stackings obtained in accordance with the process according to the invention. Example 1 (Figure 2)

[0090] In this example, reference numeral 1 designates a CMC substrate. Reference numeral 5 designates the hexagonal tantalum nitride layer deposited according to step Eadd of the present process, while reference numerals 2 and 4 designate respectively the silicon-based bonding sublayer implemented according to step El and the environmental barrier coating implemented according to step E2, which is based on ytterbium disilicate.

[0091] Here, the Eadd step is implemented before the EL step

[0092] In this example, the sub-layer 2 has a thickness of 80 micrometers and is produced by vacuum plasma spraying, while the coating has a thickness of 1000 micrometers and is produced by conventional air plasma spraying.

[0093] Layer 5 has a thickness of 1 micrometer and is produced using the aforementioned HIPIMS process. Example 2 (figure 3)

[0094] In this example, reference numeral 1 designates a CMC substrate. Reference numeral 5 designates the hexagonal tantalum nitride layer deposited according to step Eadd of the present process, while reference numerals 2 and 4 designate respectively the silicon-based bonding sublayer implemented according to step El and the environmental barrier coating implemented according to step E2, which is based on ytterbium disilicate.

[0095] Unlike the previous example, the Eadd step is implemented after the El step and before the E2 step.

[0096] In this example, the sub-layer 2 has a thickness of 80 micrometers and is produced by vacuum plasma spraying, while the coating has a thickness of 1000 micrometers and is produced by conventional air plasma spraying.

[0097] Layer 5 has a thickness of 1 micrometer and is produced using the aforementioned HIPIMS process. Example 3 (figure 5)

[0098] This example has the same characteristics as the previous example.

[0099] It differs from it, however, in that a layer 6 of metallic tantalum is inserted between layer 2 and layer 5 in order to limit the diffusion of nitrogen from tantalum nitride to silicon and the formation of silicon nitride SiN.

[0100] The technique according to the invention therefore provides the following functionalities and advantages:

[0101] - the reflection of a high fraction of the radiative flux allowing to decrease the SiC / SiC substrate interface temperature - environmental barrier system;

[0102] - resistance to oxidation and corrosion at temperatures of interest;

[0103] - possibly to reduce crack propagation through multiple interfaces generated within this coating when it is deposited in a multilayer form caused by thermal cycles.

[0104] These functionalities are in addition to those provided by the environmental barrier, thereby increasing its lifespan.

Claims

Demands

1. A method for coating a substrate (1) of silicon-containing ceramic matrix composite material with at least one coating (4) forming an environmental barrier, comprising the following steps: E1: formation of a silicon-based bonding sublayer (2) over said ceramic matrix composite material substrate (1); E2: formation of an environmental barrier coating (4) over said silicon-based bonding sublayer (2), characterized in that it comprises an additional step Eadd of forming at least one hexagonal phase TaN layer (5) over or under said silicon-based bonding sublayer (2).

2. A method according to claim 1, characterized in that said additional step Eadd is implemented so as to form said at least one layer of hexagonal phase TaN (5) below said silicon-based bonding sublayer (2), such that said at least one hexagonal phase TaN layer (5) is intercalated between said silicon-based bonding sublayer (2) and said ceramic matrix composite material substrate (1).

3. A method according to claim 1, characterized in that said additional step Eadd is implemented so as to form said at least one layer of hexagonal phase TaN (5) above said silicon-based bonding sublayer (2), so that said at least one layer of hexagonal phase TaN (5) is intercalated between said silicon-based bonding sublayer (2) and said environmental barrier coating (4).

4. Method according to claim 3, characterized in that at least one metallic tantalum layer (6) is formed between said silicon-based bonding sublayer (2) and said at least one hexagonal phase TaN layer (5).

5. A method according to any one of the preceding claims, characterized in that said additional step Eadd is implemented by a high-power pulsed cathodic sputtering process.

6. A method according to any one of claims 1 to 5, characterized in that said additional step Eadd is carried out until a layer of thickness of between 1 nanometer and 50 micrometers, preferably between 20 nanometers and 5 micrometers, is obtained.

7. A method according to any one of claims 1 to 6, characterized in that said at least one layer of hexagonal phase TaN (5) has a minimum hemispherical reflectivity of 50% in the range of wavelengths between 0.1 and 6 micrometers.

8. A method according to any one of claims 1 to 7, characterized in that said additional step Eadd comprises the formation of at least two distinct layers of TaN in hexagonal phase (5).

9. A method according to any one of claims 1 to 8, characterized in that said silicon-based bonding sublayer is formed of silicon, boron-doped silicon, hafnium oxide-doped silicon, rare earths consisting of yttrium, ytterbium and gadolinium with dopant additions consisting of zirconium, hafnium, tantalum, nitrogen, aluminum, SiAlON, Si-HfB2, SiC-HfO2, or SiC-HfO2-HfB2.

10. A process according to any one of claims 1 to 9, characterized in that said step El is carried out by implementing one of the following processes: physical evaporation deposition PVD, atmospheric pressure plasma spraying APS, high-speed flame powder deposition HVOF, low-pressure plasma spraying LPPS, inert atmosphere plasma spraying IPS, chemical evaporation deposition CVD, vapor aluminization APVS, flash sintering, electrolytic deposition, slurry, sol-gel.

11. A method according to any one of claims 1 to 10, characterized in that said environmental barrier coating (4) is selected from rare earth disilicates Re2Si2O7 (where Re = Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Yb, Dy, Ho, Er, Tm, Tb, Lu) and the corresponding co-doped disilicates, rare earth silicates Re2SiO5 and the corresponding co-doped silicates, barium strontium aluminosilicate (BaO)x.(SrO)i x.Al2O3.2SiO2 with 0 < x < 1), hafnium-doped rare earth silicates, rare earth-doped hafnium, mullite, spinels MgAl2O4, garnets (Y3Al2O50i2 ), partially / totally stabilized and possibly doped zirconias, A4B30i2 delta phases where A = yttrium, lanthanum or lutetium and where B = zirconium or hafnium, composites including Y2O3 in combination with ZrO2 and / or A12O3 and / or TiO2, hexa-aluminates, complex perovskites, and mixtures of at least two of these components.

12. A method according to any one of the preceding claims, characterized in that said step E2 is carried out by one of the following methods: atmospheric pressure plasma spraying (APS), vacuum plasma spraying, plasma spraying, including under very low pressure, suspension plasma spraying (SPS), solution plasma spraying (SPPS), high-speed flame powder spraying (HVOF), high-speed flame liquid spraying (HVSFS), electron beam evaporation (EB-PVD), PVD vapor phase deposition, sol-gel, slurry, electrophoresis, or flash sintering.

13. A method according to any one of the preceding claims, characterized in that said substrate (1) is a constituent of a turbomachine part, such as a blade, a distributor and / or a ring sector of the high-pressure turbine.

14. Part comprising a substrate (1) of silicon-containing ceramic matrix composite material, particularly for aeronautical applications, comprising: - a silicon-based bonding sublayer (2) above said ceramic matrix composite material substrate; - an environmental barrier coating (4) above said silicon-based bonding sublayer (2); characterized in that it also comprises at least one hexagonal phase TaN layer (5) above or below said silicon-based bonding sublayer (2).

15. Part according to claim 14, characterized in that said at least one layer of hexagonal phase TaN (5) is intercalated between said silicon-based bonding sublayer (2) and said ceramic matrix composite material substrate (1).

16. Part according to claim 14, characterized in that said at least one layer of hexagonal phase TaN (5) is intercalated between said silicon-based bonding sublayer (2) and said environmental barrier coating (4). 14

17. Part according to claim 16, characterized in that it comprises, between said silicon-based bonding sublayer (2) and said at least one hexagonal phase TaN layer (5), at least one metallic tantalum layer (6).

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